Fire is a continuing threat to life and property throughout the world. Forest, brush and grassland fires cause enormous damage each year, not only in terms of the value of timber, wildlife and livestock destroyed, and the waste and expenditure of money and human resources in fire-fighting efforts, but also in terms of the catastrophic effect on erosion, watershed equilibrium and related problems. Similarly, fire is responsible for the loss of billions of dollars annually in the destruction of buildings, manufacturing facilities, and other man-made structures in the populated areas of the world, and is a major threat to human life.
Over the years, numerous methods for combating such fires have been developed. The use of water, foams, chemicals and other quenching materials are well known. Efforts have concentrated not only on compositions and methods for extinguishing fires already in progress, but also for the prevention of fires by pretreatment of combustible surface areas, structures, fabrics, and the like to render them less combustible. Very substantial efforts have been expended in the area of chemical retardants or suppressants, and a number of these have been adopted and used for specific purposes.
For example, borates, carbonates, bicarbonates and other salts have been demonstrated to have useful properties as fire fighting chemicals. Representative prior art patents showing such use, starting in the early part of the century, and continuing until more recent times, include U.S. Pat. No. 1,030,909 to Mesturino; U.S. Pat. No. 1,339,488 to Weiss; U.S. Pat. No. 1,813,367 Thompson; U.S. Pat. No. 2,875,044.to Dunn; U.S. Pat. No. 3,537,873 and U.S. Pat. No. 3,719,515 to Degginger; U.S. Pat. No. 4,021,464 to Mayerhoefer et al; U.S. Pat. No. 4,076,580 to Panusch et al; U.S. Pat. No. 4,095,985 to Brown; and U.S. Pat. No. 4,725,382.to Lewchalermwong. However, although the fire inhibiting properties of the borates, carbonates and bicarbonates have been established, the use of these materials has been limited because of the lack of effective means for dispensing them and their tendency to inhibit plant growth when used in larger quantities.
More recently attention has turned to other chemical agents such as the halogens (fluorine, chlorine, bromine and iodine) and halogenated compounds. Fire retardant compositions making use of these agents are illustrated in U.S. Pat. No. 3,936,414.to Wright et al and U.S. Pat. No. 3,196,108 to Nelson. See also Lyons, The Chemistry and Uses of Fire Retardants, John Wiley & Sons, 1970, pages 147, 411. Although effective in this usage, the usefulness is partially limited by the side reactions which may occur in a fire, such as the production of phosgene or diphosgene, the generation of corrosive agents, and the like.
One of the inherent difficulties with most of the chemical compositions found to exhibit fire retardant properties is that they are relatively expensive, and the cost factor militates against applying them in the large quantities as may be required, for example, in combating or preventing forest, brush and grass range fires. For this reason, a considerable amount of effort has been spent in the search for by-product or waste materials which might assist in the problem. Thus, for example, substantial research has been done to determine if calcium lignosulfonate might have any useful fire retardant properties. Calcium lignosulfonates (otherwise known as sulfite lignins or ligninsulfonates) are the waste by-products of the sulfite-pulping process of the paper industry. The sulfite process results in a spent liquor containing lignosulfonates as the principal component. Some 14%-17% of the lignosulfonates are sold for miscellaneous uses which have been developed, but the remainder must be burned or otherwise disposed of, under increasingly restrictive anti-pollution regulations.
Uses of lignosulfonates as components in fire retardant compositions are reported in prior patents such as U.S. Pat. No. 3,464,921to Erler et al; U.S. Pat. No. 3,862,854 and U.S. Pat. No. 3,962,208 to Zeigerson et al; U.S. Pat. No. 3,915,911 to Horiguchi; and U.S. Pat. No. 4,820,345 to Berg et al. Additionally, U.S. Pat. No. 2,858,895 to Connell discloses a boric acid or borate fire suppressing compound, with lignin sulfonate as a sticking agent; and U.S. Pat. No. 2,901,42 Steppe describes the use of phosphoric acid and/or boric acid or their salts as fire extinguishing compositions, with the inclusion of dried powdered sulfite waste liquor to reduce agglomeration. However, despite the effort that has been put forth, the fire suppressing properties of the lignosulfonates by themselves are not generally regarded as reliable enough to warrant commercialization. The materials may be used under certain circumstances where, because of their sheer bulk, they may extinguish small fires, but under other circumstances they are known to contribute a fueling effect to existing fires.
It is an object of the present invention to provide a modified calcium lignosulfonate which possesses significant, reliable fire suppressing properties.
It is another object of the invention to provide a modified calcium lignosulfonate which may be used to extinguish fires actually in progress, but which may also be used for the pretreatment of flammable substances to protect against fire.
It is a further object of the invention to provide a new fire retardant material from waste material in a form which is biodegradable, water reducible and non-toxic to 4 plant and animal life.
It is a still further object to provide such fire retardant material in multiple useful forms, including foams, adhesives, and the like.
It is an even further object to provide a modified inexpensive waste material having fire retardant properties of its own but which is compatible with, and useful as an extender for, other known, more expensive fire retardant materials.
Other objects and advantages will become apparent as the specification proceeds.